[FFmpeg-devel] [PATCH 1/2] configure: use proper Windows-style static library naming

[FFmpeg-devel] [PATCH 1/2] configure: use proper Windows-style static library naming

[Kacper Michajłow]

On Windows, static libraries are typically named with a .lib extension.
An exception to this is MinGW targets, which are treated as a distinct
target-os.

Using Windows-style naming allows Clang to be used as the linker driver,
instead of invoking link or lld-link directly. The latter approach
requires manually specifying standard libraries, which may be
error-prone or incomplete.

This change also improves support for LTO and sanitizer builds, where
it's significantly easier to let the compiler driver manage the
necessary linker flags.

It fixes issues where Clang is asked to `-lavcodec`, which gets passed
to the linker as avcodec.lib, resulting in an error like:
lld-link: error: could not open 'avcodec.lib': no such file or directory
This happens because `libavcodec.a` were unexpectedly generated, not
`avcodec.lib` expected by tooling.

Note that this doesn't affect mingw build. MSVC builds work the same,
because there libraries are passed as files directly to linker command.

This also removes LD_LIB from Win32/64 target as there is one type of
.lib in practice. We cannot build both shared and static as noted by the
next line.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 configure | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/configure b/configure
index e2e9fc26d8..c57da316cc 100755
--- a/configure
+++ b/configure
@@ -5062,6 +5062,7 @@ probe_cc(){
         _depflags='-MMD -MF $(@:.o=.d) -MT $@'
         _cflags_speed='-O3'
         _cflags_size='-Oz'
+        _ld_lib='-l%'
     elif $_cc -V 2>&1 | grep -q Sun; then
         _type=suncc
         _ident=$($_cc -V 2>&1 | head -n1 | cut -d' ' -f 2-)
@@ -5107,7 +5108,7 @@ probe_cc(){
         _cc_o='-Fo$@'
         _cc_e='-P'
         _flags_filter=icl_flags
-        _ld_lib='lib%.a'
+        _ld_lib='%.lib'
         _ld_path='-libpath:'
         # -Qdiag-error to make icl error when seeing certain unknown arguments
         _flags='-nologo -Qdiag-error:4044,10157'
@@ -5125,7 +5126,7 @@ probe_cc(){
         _ident=$($_cc -flavor gnu --version 2>/dev/null)
         _ld_o='-out:$@'
         _flags_filter=msvc_flags
-        _ld_lib='lib%.a'
+        _ld_lib='%.lib'
         _ld_path='-libpath:'
     elif $_cc -nologo- 2>&1 | grep -q ^Microsoft || { $_cc -v 2>&1 | grep -q clang && $_cc -? > /dev/null 2>&1; }; then
         _type=msvc
@@ -5152,7 +5153,7 @@ probe_cc(){
         _cc_o='-Fo$@'
         _cc_e='-P -Fi$@'
         _flags_filter=msvc_flags
-        _ld_lib='lib%.a'
+        _ld_lib='%.lib'
         _ld_path='-libpath:'
         _flags='-nologo'
         disable stripping
@@ -5931,9 +5932,6 @@ case $target_os in
     win32|win64)
         disable symver
         if enabled shared; then
-            # Link to the import library instead of the normal static library
-            # for shared libs.
-            LD_LIB='%.lib'
             # Cannot build both shared and static libs with MSVC or icl.
             disable static
         fi
@@ -5941,6 +5939,8 @@ case $target_os in
         enabled x86_32 && check_ldflags -LARGEADDRESSAWARE
         add_cppflags -DWIN32_LEAN_AND_MEAN
         shlibdir_default="$bindir_default"
+        LIBPREF=""
+        LIBSUF=".lib"
         SLIBPREF=""
         SLIBSUF=".dll"
         SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME)-$(LIBVERSION)$(SLIBSUF)'
-- 
2.45.1

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[FFmpeg-devel] [PATCH 2/2] configure: add -Wl when linker is called indirectly

[Kacper Michajłow]

It's possible to call linker indirectly through driver like Clang. In
which cases linker args has to be prefixed with -Wl.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 configure | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/configure b/configure
index c57da316cc..a5c3bd3917 100755
--- a/configure
+++ b/configure
@@ -5951,6 +5951,11 @@ case $target_os in
         SLIB_INSTALL_EXTRA_SHLIB='$(SLIBNAME:$(SLIBSUF)=.lib)'
         SLIB_INSTALL_EXTRA_LIB='$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
         SHFLAGS='-dll -def:$$(@:$(SLIBSUF)=.def) -implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
+        if test $ld_type = "clang"; then
+            SHFLAGS='-Wl,-dll -Wl,-def:$$(@:$(SLIBSUF)=.def) -Wl,-implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
+        else
+            SHFLAGS='-dll -def:$$(@:$(SLIBSUF)=.def) -implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
+        fi
         enabled x86_64 && objformat="win64" || objformat="win32"
         ranlib=:
         enable dos_paths
-- 
2.45.1

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